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Hi all,
I've been looking at a number of threads about supply cables (from meter/isolator to consumer unit) that are longer than 3m (as I have a few customers where this is the case) and that this requires protection at the origin of the supply in the form of a 'switch fuse'.
Obviously switch fuse is self explanatory and they are readily available from wholesalers, but then you have the RCD requirement if the cable is buried in the wall without mechanical protection etc.
So my question is this... does the use of the term 'switch fuse' preclude the use of other devices such as an RCD/MCB combination for the purpose of protecting the supply cable?
I would say the requirements are 'an ability to isolate' and 'an ability to protect against overcurrent' and therefore an RCD/MCB combination is ideal because the RCD will provide isolation (with the added benefit of earth fault protection) and the MCB will provide the required overcurrent protection. If it has to be a switch fuse, what is the reasoning behind that?
I've been looking at a number of threads about supply cables (from meter/isolator to consumer unit) that are longer than 3m (as I have a few customers where this is the case) and that this requires protection at the origin of the supply in the form of a 'switch fuse'.
Obviously switch fuse is self explanatory and they are readily available from wholesalers, but then you have the RCD requirement if the cable is buried in the wall without mechanical protection etc.
So my question is this... does the use of the term 'switch fuse' preclude the use of other devices such as an RCD/MCB combination for the purpose of protecting the supply cable?
I would say the requirements are 'an ability to isolate' and 'an ability to protect against overcurrent' and therefore an RCD/MCB combination is ideal because the RCD will provide isolation (with the added benefit of earth fault protection) and the MCB will provide the required overcurrent protection. If it has to be a switch fuse, what is the reasoning behind that?